SPAD Light Sensor Correlation Circuit for LED ToF Distance Sensing
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Solution Overview
Problem
LIDAR systems for obstacle detection in vehicles are costly, difficult to integrate with other systems, and require powerful computation, making them expensive and power-consuming.
Innovation Solution
A light sensor using a single-photon avalanche diode (SPAD) circuit with a voltage-modulated binary code for demodulation and correlation, integrated with an integrator circuit to measure time of flight (ToF) without requiring strong processing means, and a lighting circuit with incoherent LEDs for object detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If LIDAR systems use laser diodes for obstacle detection, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent changes the light source parameter from coherent laser diodes to incoherent LEDs, and changes the detection method parameter from direct time measurement to correlation-based ToF measurement. This allows integration with automotive headlight systems while maintaining distance measurement capability through code modulation and correlation processing.
Solution Approach 2:
The patent uses code modulation (copying the binary code pattern) to encode the light emission, then correlates the received signal with the original code to determine time of flight. This copying approach enables precise measurement without requiring complex laser systems.
2Measurement precision
If LIDAR systems use laser diodes for obstacle detection, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The patent changes the light source to LEDs which consume less power than laser diodes, and changes the processing approach from high-frequency direct time measurement to correlation-based processing that reduces computational power requirements and associated energy consumption.
3Measurement precision
If LIDAR systems use strong computation means for signal processing, then measurement precision is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent uses code copying and correlation - the transmitted binary code is copied and used as a reference for correlating with the received signal. This approach simplifies processing compared to direct time measurement while maintaining precision through the correlation peak detection.
Solution Approach 2:
The patent replaces complex high-frequency time measurement electronics with a correlation-based processing system that uses code modulation and comparison, reducing the computational complexity and hardware requirements while maintaining measurement precision.
4Measurement precision
If LIDAR systems use laser diodes for obstacle detection, then measurement precision is improved, but ease of manufacture worsens
Solution Approach 1:
The patent changes the light source parameter to LEDs which are easier to manufacture and integrate with automotive headlight systems. The detection method is changed to correlation-based ToF measurement that works with incoherent light sources, enabling direct integration with existing headlight infrastructure.
Solution Approach 2:
The patent makes the lighting system universal by using LEDs that serve both as headlight illumination and as LIDAR light sources. The correlation-based detection method is universally applicable to incoherent light sources, enabling multi-functionality and easier integration.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables efficient and cost-effective obstacle detection by directly providing a distance image with reduced computational and power requirements, allowing integration into vehicles like headlamps.
Implementation Method 1
at least one single-photon avalanche diode (SPAD) circuit comprising at least one SPAD
Implementation Method 2
single-photon avalanche diode (SPAD) circuit comprising at least one SPAD
Data Source
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AI summary
The invention relates to a lighting circuit having a light sensor configured to measure a delay of reception of light that is being modulated based on a binary code after a reflection, said binary code being repeated for a predetermined time period T. The light sensor comprises: - a single-photon avalanche diode (SPAD) circuit (320) comprising a SPAD polarized by a voltage modulated by the code delayed of time k*ΔT, - an integrator (330) connected to the SPAD circuit (320) for providing an integration value of the conduction time of a SPAD (321) for each time the code is completely received.